Surgical staplers are frequently used in surgical procedures for suturing body tissues such as, for example, intestinal and gastric walls. Such devices typically include a staple holder, or cartridge, which is disposed on one side of the tissue to be fastened and an anvil assembly on the other side of the tissue. During the surgical procedure, the staples are driven from the cartridge by some type of actuator so that the ends of the staples pass through the tissue and then are bent inwardly by the anvil so as to produce an array of finished fasteners in the tissue. During the typical suturing process, pusher members associated with the cartridge are controllably advanced by the operating mechanism of the instrument in a manner to urge the staples out of the cartridge, through the tissue and forceably against the anvil.
One such frequently used type of surgical stapler is the open linear stapler, which is a device that enables the surgeon to simultaneously place one or more rows of surgical staples in body tissue or organs. By way of example, a typical procedure is a pneumectomy, which is a removal of a portion of the patient's lungs. The linear stapler can be used several times during this procedure, including for the occlusion of the pulmonary artery prior to its resection. For this later use, the surgeon first clamps the jaws of the stapler across the artery then forms the staple and before reopening the stapler jaws, cuts the artery with a scalpel using the edge of the staple jaws as a guide.
An example of an open linear stapler is disclosed in U.S. Pat. No. 5,706,998 issued to Plyley et al. A surgical stapler is described having a supporting frame including a stationary jaw having an anvil, a movable jaw, a replaceable staple cartridge carried by the movable jaw, a mechanism for approximating the cartridge relative to the anvil, and a mechanism for firing the device so as to crimp the staples against the anvil in a manner to enable the surgeon to substantially simultaneously place one or more rows of surgical staples in organs or tissues. The device includes interrelated, cooperating first and second locking mechanisms for positively preventing refiring if the staple cartridge is spent and for providing a tactile sensation to the surgeon to indicate that a spent staple cartridge is present within the instrument. One of the drawbacks to this design is the large amount of force required for the surgeon to fire the staples using the firing mechanism. Having an open linear stapler with a large amount of force required for the surgeon to fire the staples limits the number of surgeons that can actually use the device because of the strength required to actuate the firing mechanism. Another drawback of this design is the fact that no cutting means, or knife, is available to use after the staples have been fired.
Another example of an open linear stapler is disclosed in U.S. Pat. No. 3,692,224 issued to Astafiev et al. A surgical stapling apparatus is described including a support housing having an open longitudinal cavity wherein slidable rods of the staple housing and pusher are accommodated. The staple housing has a head provided with a socket in which a magazine with staples in entirely inserted. The staple housing and the pusher are provided with screw drives to axially shift them relative to the support housing. The apparatus also includes a limit strip capable of retaining the magazine when it is completely pushed into the socket and holding the tissue being sutured. The limit strip interacts with the nut of the drive of the staple housing whereby the drive of the pusher is blocked with the drive of the staple housing in such a manner that a predetermined sequence of actions is provided during the operation of the apparatus. In accordance with this sequence, the staple housing can move only after the magazine is completely pushed into the socket of the staple housing and the pusher can displace only after the staple housing has defined for a maximal suturing gap between the working surface of the magazine and the die. One of the drawbacks of this design is the inability to grasp the tissue and secure it prior to firing the staples. Without being able to secure the tissue, if a surgeon slips firing the device, he or she may misplace the staples from their intended position. Another drawback of this design is the fact that no cutting means, or knife, is available to use after the staples have been fired.
The prior art open linear staplers all exhibit one or more drawbacks that have thus far limited their usefulness to the surgeon using these open linear staplers. What is needed therefore is an open linear stapler that has a low actuation force required to fire the staples and an integrated knife, which also cuts with this low actuation force.